1. Field of the Invention
The present invention relates to an image apparatus, for example a digital still camera. In particular, it relates to a displaying technology in operations of a manual focus mode and a zoom mode.
2. Description of the Related Art
Conventionally, an image apparatus such as a digital still camera includes a small LCD (Liquid Crystal Display) as a display device. The display device displays an image to be captured in real-time. In a case of operating in a manual focus mode, the operator confirms the image on the display device and carries out a release operation for photographing when the object is in focus.
However, the screen of the general display device in the image apparatus is small and has a low resolution, and just shows the image in a decreased size and decreased number of pixels. Because of the low resolution of the screen, even though the operator thinks an object is in focus through the display device, the object may not actually be in focus. In other words, the operator may not be able to evaluate the degree of focus through the display device.
Some digital still cameras have a function to evaluate the degree of focus correctly in a case of operating in the manual focus mode. That function is that an output from a part of the image capturing device (CCD) is read out to recognize a focus and the output is enlarged on the screen of the display device to indicate the degree of focus.
In such a manner, the operator can decide the degree of focus by a part of the image and take a photograph with correct focus. However, the operator can not see the entirety of the image since the screen just shows the part of the image. The operator can not recognize a whole area to be photographed.
Some digital still cameras have a zoom function. In a case of using the zoom function, the display device only shows the image of the object which is zoomed. The operator may miss the object when the object moves fast. Further, if the object is affected by changes around the object, the operator may miss a timing of the release operation.
Japanese laid open patent 2007-43502 discloses that an image apparatus includes a main light detecting unit having a zoom lens, a sub light detecting unit having a single focus lens, and a display unit. The display unit shows both main image data from the main light detecting unit and sub image data from the sub light detecting unit. The display unit highlights the area corresponding to the main image data in the sub image data.
According to the apparatus of Japanese laid open patent 2007-43502, the image display shows two images to prevent the object from being out of the photograph. One image is main image data which is enlarged in a live view (monitoring) of the object with optical zoom. The other image is sub image data which is in a live view of both the object itself and around the object. In the sub image data, the part of the main image data is surrounded by a frame border.
In a case of operating in a manual focus mode, both an image that is an enlarged part of the entirety to be photographed and an image of the entirety to be photographed are displayed in the same display device. The operator can then confirm the degree of focus and the composition of the entirety to be photographed.
However, when a first image that is the enlarged part of the entirety to be photographed and the second image of the entirety to be photographed are displayed in the same display device, a difference of display timing between the first image and the second image occurs since there is a difference of frame rate between the respective images. The operator may have a feeling of unease or strangeness by the difference of the display timing, and may then miss the photo opportunity when the object moves fast. It then is still difficult for the operator to evaluate the degree of focus correctly.